lvds

The Thinkpad X220 is almost a perfect laptop. The X220 is small, light, was the last small Thinkpad to use 35W CPUs, has great Linux support, incredible battery life, and can be found used very inexpensively. For the Thinkpad Mafia, the X220 is a badge of honor, but it does have one glaring drawback: the LCDs in these laptops are capped at 1366×768 resolution.

A few wizards in Japan and China have taken up the X220 and developed an adapter to give this tiny laptop the display it deserves. Mentions of a FHD mod – the Lenovo-speak for a Thinkpad display upgrade – can be found on Taobao, but the anglosphere doesn’t get these cool toys. [Vectro] decided his X220 wasn’t up to snuff and decided to build his own Thinkpad mod to give his trusty companion a bigger and brighter display. He succeeded, and did it in a way that’s much better than any previous attempt.

Stock, the X220 uses an LVDS bus for internal video, and there aren’t enough lanes on this bus for a 1080 display. The usual way of modifying the X220 for a display with higher resolution is tapping into the eDP present on the Thinkpad dock connector. [Vectro]’s solution differs slightly from the usual way of doing things – instead of using an I2C EEPROM to report the resolution, DPI, and model of display, he’s using a microcontroller. This gives him the ability to control the power state and brightness level of the display. It’s a great solution, and is designed to be a relatively easy drop-in mod.

The new display works, and Thinkpadding at 1080 is awesome, but there’s still work to be done. The dock connector is incompatible with this mod, and hopefully scaling this up for small-scale production. Producing a few X220 FHD kits is going to be a problem, as each wire in the eDP cable is individually soldered to the connector. It doesn’t scale well, but there is certainly a demand to make the greatest Thinkpad even better.

Every year, new models of laptops arrive on the shelves. This means that old laptops usually end up in landfills, which isn’t exactly ideal. If you don’t want to waste an old or obsolete laptop, though, there’s a way to reuse at least the screen out of one. Simply grab an FPGA off the shelf and get to work.

[Martin] shows us all how to perform this feat on our own, and goes into great detail about how all of the electronics involved work. Once everything was disassembled and the FPGA was wired up, it took him a substantial amount of time just to turn the display on. From there it was all downhill: [Martin] can now get any pattern to show up on the screen, within reason. The only limit to his display now seems to be the lack of external RAM. He currently uses the setup to drive an impressive-looking clock.

This is a big step from days passed where it was next to impossible to repurpose a laptop screen. Eventually someone discovered a way to drive these displays, and now there are cheap electronics from China that can usually get a screen like this running. It’s impressive to see it done from scratch, though, and the amount of detail in the videos are a great way to understand how everything is working.

We have talked about a whole slew of logic and interconnect technologies including TTL, CMOS and assorted low voltage versions. All of these technologies have in common the fact that they are single-ended, i.e. the signal is measured as a “high” or “low” level above ground.

This is great for simple uses. But when you start talking about speed, distance, or both, the single ended solutions don’t look so good. To step in and carry the torch we have Differential Signalling. This is the “DS” in LVDS, just one of the common standards throughout industry. Let’s take a look at how differential signaling is different from single ended, and what that means for engineers and for users.

Single Ended

Single Ended: TTL, CMOS, LVTTL, Etc.

Single Ended and Sources of Noise

Collectively, standards like TTL, CMOS, and LVTTL are known as Single Ended technologies and they have in common some undesirable attributes, namely that ground noise directly affects the noise margin (the budget for how much noise is tolerable) as well as any induced noise measured to ground directly adds to the overall noise as well.

By making the voltage swing to greater voltages we can make the noise look smaller in proportion but at the expense of speed as it takes more time to make larger voltage swings, especially with the kind of capacitance and inductance we sometimes see.

Differential

Enter Differential Signaling where we use two conductor instead of one. A differential transmitter produces an inverted version of the signal and a non-inverted version and we measure the desired signal strictly between the two instead of to ground. Now ground noise doesn’t count (mostly) and noise induced onto both signal lines gets canceled as we only amplify the difference between the two, we do not amplify anything that is in common such as the noise.

Everybody loves cheap stuff, and we hate telling everyone about coupon codes. That said, TI has a new LaunchPad development board they’re promoting. It’s based on the MSP432, the ARM extension of their MSP430 line. The MSP432 is an ARM Cortex M4F, low power, and planned for production later this year.

Here’s your daily CES garbage post. Through a collaboration between Sony and Nissan, a car has become a video game controller controller. A controller plugs into the ODB II port, reads throttle, brake, and steering wheel positions (and buttons on the dash/steering wheel, I guess), and translates that into controller input for a PlayStation 4. What games do they play with a car? You would think Gran Turismo, Rocket League, or other games with cars in them. Nope. Football.

Dangerous Prototypes is a legal Chinese company! [Ian] didn’t say anything about the process about becoming a legal Chinese company because he wrote a blog post, not a book. Shenzhen Dangerous Prototypes Electronics Technology Limited allows them to have an office in the Shenzhen electronics market, hire local and foreign hackers, host Hacker Camp Shenzhen, and allow people to apply for ‘Authorized Authority’ visa letters for the people who need them. Great news for a great company.

The Forge hackerspace in Greensboro, NC is growing. In just over a year they have 160 members and they’ve already outgrown their 3,400 square foot space. Now they’re moving to a larger space that’s twice the size and they’re looking for donations.

People have been taking old iPad screens and turning them into HDMI displays for years now. [Dave] got his mitts on a panel from a Macbook Pro 17″, and turned it into a monitor. It required a $50 LVDS adapter, but the end result is great – a 1920×1200 panel that looks pretty good.

You have an old PC with a nonstandard RGB video out and you need to bring it to a modern PAL TV set. That’s the problem [svofski] had, so he decided to use an Altera-based DE1 board to do the conversion. Normally, you’d expect reading an RGB video signal would take an analog to digital converter, which is not typically present on an FPGA. Instead of adding an external device, [svofski] used a trick to hijack the FPGA’s LVDS receivers and use them as comparators.

No doubt anyone reading this has access to a few ancient laptops and the displays contained within. While those laptops are probably still stuck with a Gig of RAM and Windows ME, the display panels are probably still good. They don’t have HDMI, DVI, or VGA, though, which means those panels will need a converter.

[Jared] had a very cool sunlight-readable ‘transflective’ LCD from on old Portege R500 laptop. If he was going to take apart one laptop to use with modern hardware, this was the one. Opening up the display he found a tiny connector but no obvious markings of what pins did what. The datasheet was also not to be found. By shorting two pins together, he could figure out what the pins were: shorting the clock freezes the screen, shorting the HSYNC and VSYNC means the screen loses sync. Blues, reds, and greens can be found the same way.

With the pins identified, a breakout board was in order. This is just a small board to break out the very small wires to solderable pads and a driver for the backlight. With that, and the RIoT with an LVDS output, [Jared] was able to use new hardware with this old but still serviceable display.

Regular reader and master hacker [Bill Porter] got married. Congratulations [Bill] and [Mara]! The two of them just couldn’t leave their soldering irons at home. The actually swore their vows by soldering together a circuit during the ceremony (blinky wedding dress, el wire tuxedo, and all).

[Kevin] sent in a link to [Red Fathom’s] hacked Wacom tablet. It’s the screen from a Wacom-enabled laptop brought back to life with a Teensy and an LVDS interface module.